Business leaders say that the tube strikes will cost London's economy £200m in losses as the first of two planned, 48-hour walkouts creates travel chaos for millions of commuters.

According to the London Chamber of Commerce, the London underground strikes will cost the capital's economy £50m a day, following a hit on tourist and retail trades.

The Rail, Maritime and Transport Workers Union (RMT) and the Transport Salaried Staffs Association walked out for 48 hours from 9.30 GMT on 4 February in a row over 953 job losses stemming from the closure of ticket offices.

Prime Minister David Cameron slammed the strikes and the cost to the economy as "shameful" and challenged the opposition to make a comment over the walkouts.

"(RMT union leader) Bob Crow's Tube strike is plain wrong and he should call it off today.

"His shameful plans will bring misery to millions of hardworking families in London. [Labour's] Ed Miliband should condemn the strike immediately — no ifs and no buts."

Earlier this week, the union's boss Crow used a press conference to try and justify the mass strike action, which is set to be repeated on 11 February.

"More and more people want to use the underground and you're going to take around 800 jobs away to deal with those people," said Crow.

"[The ticket office supervisors] play a crucial role. They are visual, they've got experience, and when the [7/7] bombings took place by the vicious terrorists in London, these are the people who came from behind the back of the booking offices to support those group of passengers who were travelling around London to get them to a safe place."

However, his statement came amid reports that he recently enjoyed a £10,000 holiday.

In response to an accusation by a reporter that he was a distraction from the issue at the heart of the dispute, Crow denied that the unions' objectives was undermined by his high profile and stressed that his holiday was "booked up well before" the strike action.

"If I'm going to spend £10,000 on a car, or if I'm going to spend £10,000 on a holiday, or £10,000 on cigarettes, that's up to me," said Crow.

"I'm not being a distraction at all. What do you want me to do? Sit under a tree and read books of Karl Marx every day?"